Results Compared with placebos, those receiving the active capsules
committed an average of 26.3% (95% CI 8.3-44.33%) fewer offences
(P=0.03, two-tailed). Compared to baseline, the effect on those
taking active supplements for a minimum of 2 weeks (n=172) was an
average 35.1% (95% CI 16.3-53.9%) reduction of offences (P<0.001,
two-tailed), whereas placebos remained within standard error.

Conclusions Antisocial behaviour in prisons, including violence, are
reduced by vitamins, minerals and essential fatty acids with similar
implications for those eating poor diets in the community.

Most research into factors involved in antisocial behaviour investigates
societal factors. This has produced important correlational evidence but does
not demonstrate that such factors have causal relationships with antisocial
behaviour, as this requires more rigorous experimental designs
(Altman, 1991;
Rutter, 1995). Such designs
are difficult to achieve in sociological research, which leaves questions of
volition, culpability, prevention and rehabilitation open, if cause and effect
are more precisely understood. It is noteworthy that a Director of the US
National Institute of Mental Health suggested that treatment programmes for
offenders tend not to be rigorously evaluated: ‘It's easy to fool
yourselves about efficacy if you haven't done a proper clinical trial’
(Marshal, 2000). It has,
however, been suggested that deeper knowledge of the biology of antisocial
behaviours will help interventions (Stone
& Kelner, 2000).

Background

When Sinclair persuaded the wartime British government in 1942 to
supplement the diet of all children with cod-liver oil and orange juice, he
speculated that among other ills, poor diets could lead to antisocial
behaviour. Since that time, evidence has grown to support this link
(Moynahan, 1976;
Virkkunen & Huttunen,
1982; Benton & Cook,
1991; Stevens et al,
1995,
1996;
Hamazaki et al, 1996;
Schoenthaler et al, 1997;
Walsh et al, 1997;
Hibbeln et al, 1998;
Bjork et al, 1999;
Golomb et al, 2000). If there
is a causal relationship between micronutrient deficiencies and antisocial
behaviour, then where such deficiencies exist supplementing the diet with
appropriate nutrients should improve behaviour. With the approval of the Home
Office, this was tested empirically. The study was approved by the University
of Surrey Ethics Committee and conformed to the Declaration of Helsinki. The
findings have been subject to a 10-month Home Office review.

METHOD

Experimental study

Participation

Before recruitment, the purpose of the project was explained carefully to
each participant. Participants had to be 18 years of age or over. Each
volunteer recruited (n=231) signed an informed consent form, which was
countersigned by a member of the prison staff. The trial had to conform to the
normal operations of the institution where participants would leave for
reasons such as parole or requirements of cell space. Thus, the analysis
allowed for participation to vary from a minimum period of 2 weeks to 9 months
in both baseline and supplementation periods. The average time spent on
supplementation was 142 days for the placebo group and 142.62 for the active
group. No individuals were withdrawn as a result of ill effects from
supplementation. Participants were debriefed about their participation by
written report.

Materials

It was agreed with the HM Prison Service and the Home Office to use
nutritional supplements that were available ‘over the counter.’
Although improvements in dietary intakes of micronutrients could be achieved
through diet, nutritional supplements provide a known quantity of
micronutrients and allowed for the use of a double-blind, placebo-controlled
design to test the hypothesis that supplementary vitamins, minerals and
essential fatty acids would significantly reduce the rate of disciplinary
incidents. An expert advisory group with no commercial interest in the outcome
undertook the selection of nutritional supplements, based on formulation. The
University of Surrey conducted assays to check manufacturing tolerance and
assessed the match between active and placebo supplements. The vitamin/mineral
supplement ‘Forceval’ is licensed for prescription purposes in the
UK as a therapeutic adjunct where intake of vitamins and minerals is
sub-optimal (UK product licence number PL 0528/5008R). It is formulated in
line with European Economic Council Directive 90/496/EEC on international
labelling for foodstuffs (24 September 1990) and the UK Dietary Reference
Values for Food Energy and Nutrients for the United Kingdom
(Department of Health, 1991).
Potency is presented in Table
1. A vegetable oil-based placebo with an identical opaque
bi-coloured gelatine shell was employed.

Both omega-6 and omega-3 essential fatty acids have been found to be
deficient among violent offenders (Corrigan
et al, 1994). For this reason, an essential fatty acid supplement
was also employed. ‘Efamol Marine’ provides omega-6 and omega-3
essential fatty acids without an obvious after-taste, a factor that could
otherwise have compromised the blind. The daily dosage was four capsules
providing 1260 mg linoleic acid, 160 mg gamma linolenic acid, 80 mg
eicosapentaenoic acid and 44 mg docosahexaenoic acid. A vegetable oil-based
placebo of identical colour and clear gelatine shell was used.

Measurements

Antisocial behaviour

Antisocial behaviours resulting in disciplinary action were adjudicated
through Governor or minor reports. Governor reports adjudicate more serious
incidents such as those involving violence and may involve loss of remission.
Minor reports typically adjudicate on a failure to comply with requirements.
The construction of the offence and the standard of proof ‘beyond
reasonable doubt’ was the same for both types of report. Thus, Governor
and minor reports proven in adjudication, over a specified time period, formed
the measurement of antisocial behaviour. Before breaking the blind, Governor
and minor reports were categorised into those occurring during the baseline or
supplementation period for each participant.

Dietary intake

The dietary intake of the participants was assessed using 7-day food
diaries. The nutrient content of each prisoner's diet was determined using a
database based on McCance and Widdowson's The Composition of Foods
(Holland et al, 1996). As all
foods consumed by the prisoners originated in the prison, it was possible to
devise a diary where the participants indicated which of the available choices
they had eaten and how much (a quarter, a half, three-quarters portion, all or
a second portion). Portion weights were determined from the serveries. They
were asked to report the number of items consumed, including spread on bread
and milk and sugar in beverages. A list of food items (e.g. chocolate) that
could be purchased from the prison shop was also included to record
consumption. The quantity and type of all food consumed was entered into a
computer package (‘Superdiet’) for each of the 7 days.

Procedures

Supplement distribution

Nutritional supplements were packed into blister packs containing one
vitamin/mineral capsule and four essential fatty acid capsules. Blister packs
contained either all active or all placebo supplements and were stamped with
an 11-digit alphanumeric code during manufacture. To facilitate double-blind
allocation, research staff were only provided with details of the respective
alphanumeric code allocated for each participant. Each day, coded packs were
labelled with the participant's name, cell and prison number, and as prison
officers routinely locked inmates in their cell at lunchtime they also gave
the packs to participants. Compliance was monitored and logged through
officers returning the used packs each day and routine cell searches. The log
recorded if a participant's supplement packs were returned empty, full or at
all. The HM Prison Service gave permission for the trial under the Declaration
of Helsinki on the understanding that we provided active nutritional
supplements for 3 months after the trial, so that all participants received
benefit.

Randomisation

Participants initially entered the trial enbloc at its commencement in
September 1996. They underwent psychometric assessment and their baseline
disciplinary records were obtained. A stratified randomisation was conducted
on the population of participants in each of the four main wings of the
institution, employing a random number generator to allocate to groups. Thus,
each wing formed a stratum so that the placebo and active groups were matched
in terms of disciplinary incidents and also progress in the prison regime.
Participants that were recruited subsequently over the following 8 months were
first grouped by their location (wing) and then randomly allocated to
treatment conditions using a random number generator.

Statistical analysis

Disciplinary data were analysed using negative binomial (mixed Poisson)
regression analysis (Lawless,
1987). This analysis was used because disciplinary incidents
constitute a series of discrete events over time and the basic model for this
is a Poisson process, which cannot have normal distribution. In a Poisson
process, however, it is assumed that the average probability of a person
committing an offence remains constant over time and is independent of
previous outcomes. Because we knew some individuals were more prone to
behaviour resulting in disciplinary incidents than others, we accounted for
these variations in the individual rates of disciplinary incidents by
modifying the Poisson distribution into to a negative binomial distribution.
Goodness-of-fit tests confirmed that the rates of disciplinary incidents were
indeed a good match with this predicted negative binomial (mixed Poisson)
distribution, so we were able to use this distribution as the basis for our
regression analysis. The regression was based on two main parameters, λ
and γ. The parameters λP and λA are
the mean underlying rates of disciplinary offences per day in the institution
for the placebo and active groups, respectively, and were used to compare
baseline rates of offending. The parameter γ is the ratio of the
underlying rates of disciplinary offences supplementation to baseline;
γ
P and γA being the respective ratios for
the placebo and active groups. The analysis controlled for those individuals
who had no offences at baseline and took into account how long a person had
been in the trial. Statistical power was calculated from a one-dimensional
Wald test, where the deviation of the value of γ from its hypothesised
value of unity (i.e. λ remains unchanged) in the null hypothesis is
compared to its standard error. The institution's population was typically 220
individuals. We estimated that we would recruit 75% of the population over 9
months. Taking all offences together, we estimated that statistical power for
correctly rejecting the null hypothesis, with significance at the 1% level,
would be 92%.

RESULTS

Experimental study

Compliance

Based on the daily log, the mean compliance rate for supplementation was
89.83% (95% CI 87.43-92.23%) for the placebo group and 90.67% (95% CI
88.47-92.87%) for the active group. The difference in compliance between
groups was not statistically significant (normal deviate z=-0.53).

Adverse effects

Dietary intake

Participants (n=112; 57 active, 55 placebo) completed a 7-day food diary.
Table 2 shows the average
nutrient intake of the active and placebo groups. No differences were
considered clinically significant, so the groups were considered
equivalent.

Psychometric assessment

There were no statistically significant differences between the active and
placebo groups at baseline on any of the measures of intelligence, verbal
ability, anger, anxiety, malaise and depression
(Table 3).

Placebo effectiveness

At the end of the trial, participants were asked to complete and sign a
form recording whether they thought they had received active or placebo
supplements; a total of 97 did so (Table
4). The proportions of those that guessed correctly in the active
and placebo groups were very similar and did not differ from that expected by
chance (χ2=1.26; d.f.=1, NS).

Testing the null hypothesis

The null hypothesis, that there was no difference between the change of
rates of disciplinary incidents during active and placebo supplementation
(i.e. where γA=γP), was first tested on an
‘
intent-to-treat’ basis. Here all participants (n=231) recruited
to the trial were analysed involving 532 Governor reports and 601 minor
reports. Those who received the active capsules committed on average 11.8
infringements per 1000 person-days, a reduction of 26.3% (95% CI 8.3-44.3%)
compared to those who received placebos. This difference between groups was
statistically significant at P<0.03 (two-tailed).

Actual effect of treatment on those treated

Intent-to-treat analysis is typically applied to test efficacy in the
‘
real world’ where some people do not take their medication, so it
assesses effects on the observed mixture of compliers and non-compliers. As a
consequence, it is biased towards showing no effect compared with any effect
that might occur in those actually receiving treatment
(Korhonen et al, 2000). The
intent-to-treat analysis above included 13 participants who prison staff
reported did not take their capsules, 6 who were prescribed psychotropic
medication and 40 that did not stay in the trial for 2 weeks, leaving 90
subjects who had received placebo and 82 who had received the active
supplements (Fig. 1). In
addition, the test used to reject the null hypothesis (i.e.
γ
A=γP) makes no assumption that the two
groups were matched at baseline in terms of rates of disciplinary incidents
and as such it is a good test for efficacy but a conservative test of effect.
Therefore, a more detailed analysis for the actual effect of treatment was
undertaken on these 172 participants that were treated for a minimum of 2
weeks. In this analysis, each individual becomes his/her own control, and
provided both groups are matched at baseline rates of offending, we can
predict that the rates of disciplinary incidents for the placebo group will
remain unchanged, whereas the rate should fall in the active group (i.e. where
γ
P=1, γA<1).

The null hypothesis (that there was no difference between the change of
rates of disciplinary incidents during active and placebo supplementation) was
first retested with the 172 participants (now based on 338 Governor and 416
minor reports) and once again the disciplinary infringements of those that
received active supplements fell significantly compared with those receiving
placebo (P<0.03, two-tailed). Because the null hypothesis can be rejected
with the ‘treated’ 172 participants, average compliance was high
(average 90.25%) and there were no significant differences between the groups
in compliance or drop out for other reasons (z=-0.53), we investigated
baseline rates of offending to ensure the groups were matched at baseline.

Based on 172 participants, the active and placebo groups were found to be
equivalent in average rates of disciplinary incidents prior to
supplementation. The parameters λP and λA
are the average underlying rates of disciplinary incidents for the placebo
group (n=90) and active group (n=82), respectively. Based on 754 Governor and
minor reports, λP and λA were 0.016, so
both groups would commit on average 16 disciplinary incidents per thousand
person-days. As an additional check, the minimum cut-off for length of
participation was applied at 21 and 28 days (rather than 14 days) and
consistent results were obtained.

The findings for this more specific test of the actual effect of treatment
(i.e. where γP=1, γA<1), were that the
active group showed a significant (P<0.001, two-tailed) average reduction
in disciplinary incidents, this time from 16 to 10.4 incidents per thousand
person-days, i.e. by 35.1% (95% CI 16.3-53.9%), whereas the placebo group
reduced their rate of offending by only 6.7% (95% CI -15.3 to 28.7%) (negative
figures in CI range indicate an increased rate of offending), which is again
within the standard error (P>0.1, two-tailed). It should be noted that
similar results are obtained when all participants (n=231) are included in
this form of analysis.

The greatest reduction occurred for the most serious incidents (including
violence) dealt with by Governor reports. Based on an analysis of 338 Governor
reports, the active group achieved a significant (P<0.005, two-tailed)
average reduction in Governor reports of 37% (95% CI 11.6-62.4%), whereas the
placebo group reduced their Governor reports by only a non-significant
(P>0.1, two-tailed) 10.1% (95% CI-16.9 to 37.1% (within standard
error)).

Minor reports dealt with less serious incidents (there is a degree of
overlap with Governor reports). Based on an analysis of 416 minor reports the
placebo group again showed little reduction (P>0.1, two-tailed) 6.5% (95%
CI -28.5 to 41.5 (within standard error)), whereas the active group showed a
significant (P<0.025, two-tailed) reduction in minor reports of 33.3% (95%
CI 0.9-65.7%) compared with baseline.

DISCUSSION

The experimental, placebo-controlled, double-blind methodology has
demonstrated that supplementing prisoners' diets with physiological dosages of
vitamins, minerals and essential fatty acids caused a reduction in antisocial
behaviour to a remarkable degree. It is not advocated that nutrition is the
only cause of antisocial behaviour but the difference in outcome between the
active and placebo groups could not be explained by ethnic or social factors,
as they were controlled for by the randomised design. If these findings are
replicated, and they need to be, this nutritional approach to antisocial
behaviour has the advantage that deficits in nutrition can be readily
identified and remedied.

Limitations

Interpretation

It can be argued that behaviour in institutions is untypical and this will
reduce the extent to which these findings can be broadened in their
interpretation. As a balance to this argument, the observed effect on
behaviour is physiological and unlikely to be limited to prisons as there is
no evidence that imprisonment affects the essentiality of these nutrients for
human metabolism. Indeed, a greater effect could be predicted where baseline
dietary intakes are worse. From experience, baseline dietary intakes among
serious young offenders in the community are likely to be worse than in
custody where regular meals are provided.

Statistical analysis

The analysis did not take account of the possibility that conducting such a
project in a confined setting could influence the findings. It is likely,
however, that interactions between the groups in a confined setting would
weaken any observed effect because the active group could have influenced the
atmosphere for the entire population. Hence, the findings could be an
underestimate of the true effect size. With larger institutional studies it
would be possible to test the frequencies of disciplinary offences involving
two or more individuals for randomness between groups.

Biochemical measures

Further investigations should include assessments of nutritional status
from blood before and during supplementation. Although blood analysis would
have allowed correlations between behavioural and biochemical changes, we are
confident from a considerable body of previous research (e.g.
Blonk et al, 1990;
Bunout et al, 2000) that the
nutritional supplements would have raised the prisoners' vitamins, minerals
and essential fatty acids by significant amounts. More recent research of
violent and non-violent subjects has, for example, found omega-3 plasma
essential fatty acids predicted levels of the metabolites of serotonin and
dopamine taken from cerebrospinal fluid
(Hibbeln et al, 1998).
Findings such as these suggest that further improvements in behaviour could be
achieved by providing a formulation with proportionally more omega-3 fatty
acids.

Clinical implications

Re-assessment of risk factors

If these findings are replicated, a potential implication is that the
dietary requirements for good health are also supportive of social behaviour.
Indeed, like humans, food has both a physiological and social component. This
suggests that food is an additional means to reduce antisocial behaviour but
it also may improve our understanding of established risk factors. There is a
great deal of research into factors that affect the behaviour of juveniles
(Smith, 1995,
Rutter et al, 1998), including
for instance the breakdown of families
(Heiss, 1995). However, one of
the social functions of families is to provide food, it would be illuminating
to investigate the extent to which diets are affected by such breakdowns.

Dietary education

Dietary analyses of the participants' food diaries showed that the diets
provided for the prisoners were close to current UK dietary recommendations.
We found, however, that some prisoners did not possess the most basic
knowledge to choose a healthy diet; some had not heard of vitamins. Poor food
choices by the prisoners typically resulted in lower nutrient intakes, most
notably of minerals. Despite availability, a high percentage of our
participants consumed on average less than the UK reference nutrient intakes
(RNI) of selenium (97%), magnesium (74%), potassium (74%), iodine (73%) and
zinc (66%). Although intakes below the RNI are not necessarily evidence of
inadequate intake, most micronutrients were raised significantly in the active
group by supplementation, suggesting the intervention could be welcomed on
health grounds alone. It should come as no surprise therefore that the
institution's medical staff observed no adverse reactions to supplementation
and no individuals were withdrawn as a result of supplementation. The findings
do suggest, however, a need to improve dietary education as well as providing
more nourishing diets. Indeed, one early study
(Schauss, 1978) conducted in
the community claimed that such dietary education proved more effective at
reducing recidivism than conventional probation programmes employed at that
time.

Current dietary standards

This research strongly suggests that the effect of diet on antisocial
behaviour has been underestimated and more attention should be paid to
offenders' diets. It should be noted, however, that the current dietary
standards by which dietary adequacy are judged barely take behaviour into
account. Thus, having demonstrated empirically an effect on antisocial
behaviour, we are only at the start of understanding the potential of this
intervention.

Clinical Implications and Limitations

CLINICAL IMPLICATIONS

Dietary interventions should be considered when addressing antisocial
behaviours.

Without rigorous experimental designs, nutritional effects on antisocial
behaviours may be subsumed within effects currently attributed to social risk
factors.

Dietary standards should be re-assessed to take account of behavioural
effects.

LIMITATIONS

Behavioural effects may be most apparent in those consuming the poorest
diets.

Reductions in antisocial behaviours attributed to nutrition may be
underestimated due to interactions between groups in prison.

Biochemical measures were not available and will be required in any
replication to explore the utilisation of nutrients and also mediating
mechanisms.

Acknowledgments

The research was conducted with the permission of the Home Office and HM
Prison Service. It was supported by charitable donations to the charity
Natural Justice by the Hayward Foundation, the AIM Foundation, the Wacker
Foundation, the Wates Foundation, the Esmée Fairbairn Foundation, the
Allen Lane Foundation, the Appeldore Trust, Hugh Cavendish Charitable Trust,
the Sir Charles Jessel Charitable Trust, Larkhall Laboratories, Group 4 Prison
Services Ltd and the Home Office.

Note: The research was conducted under the auspices of the charity Natural
Justice with the involvement of the Home Office throughout its development and
evaluation. Donations to Natural Justice had no commercial undertakings
whatsoever and were arranged during the chairmanship of the Right Reverend
Bishop Montefiore and The Earl Kitchener. Although Larkhall Laboratories and
Group 4 Prison Services Ltd both made modest donations to the work accounting
for 3.5% of costs, the terms of their charitable donations were the same as
grants from the grant-making trusts where no commercial arrangements were
entered into whatsoever. In addition, the Home Office required that both
supplement manufacturers provide letters stating that they would not seek
commercial advantage from advertising the selection of their products other
than being cited in the report of the findings. The Home Office subsequently
made a modest contribution to Natural Justice when the findings were
accepted.